| Diesel engine exhaust has a high proportion of nitrogen oxides,carbon monoxide,unburned organic hydrides and soot particles（PM）.These pollution components will bring serious pollution problems to the air environment,and will bring a non-negligible impact on human physical and mental health,such as asthma,cardiovascular disease and lung cancer.Soot particles have a high ignition temperature and can only be completely burned when the temperature is higher than 600℃,so there is a high requirement for tail gas catalytic treatment technology,the key is to improve the catalytic oxidation performance of catalyst at low temperature.Traditional precious metal catalysts are difficult to be popularized due to their high cost and poor stability.Cu-based catalyst and Ce-based catalyst have good application value because of their good economy and high activity.Cobalt-manganese spinel is also widely used in this field because of its stable structure.Therefore,Cu-CoMn2O4 catalyst and Ce-CoMn2O4 catalyst were prepared in this paper and their catalytic activity and stability were studied to explore the influence of the load ratio of the supporting metal on the performance of the catalyst.In addition,cu-based nanowire catalyst with nanowire morphology was prepared,and the performance of the catalyst was analyzed to study the influence of various factors on the catalytic performance.The active metal load is one of the key factors affecting the performance of catalyst.Therefore,this paper designed catalysts with different load ratios of active metals to explore the optimal catalytic performance of the load metal ratio.At the same time,the physical and chemical properties of the catalysts were characterized by scanning electron microscopy,hydrogen temperature programmed reduction,X-ray diffraction,thermogravimetry,Raman spectroscopy,infrared spectroscopy and other experiments.The main research results are as follows:（1）CuxCo1-xMn2O4 catalyst（x=0.2,0.4,0.6,0.8）was prepared by reverse deposition in a certain proportion using colloidal crystal template method.The results showed that increasing the amount of Cu doping could significantly improve the soot catalytic performance of CuxCo1-xMn2O4 system,so that the catalyst could catalyze soot particles at low temperature,and effectively reduced the reaction temperature of soot.（2）By changing the load ratio of the supported metal,the performance of the catalyst showed a specific law of change,that was,the catalytic performance increased with the increase of the supported metal.The CuxCo1-xMn2O4 catalyst（x=0.2,0.4,0.6,0.8）had the best performance when the Cu to Co element ratio was 4 to 1.The stability test of the catalyst was carried out.After three cycles of use,the catalyst still maintained similar activity to the previous one.The catalyst was stored for a long time,followed by hydrogen programmed temperature,and the experiment showed that the catalyst after a long time still had similar reducibility to the previous.The above experiments showed that the prepared catalyst had good stability.（3）The preparation period of catalyst could be effectively reduced by using the modified colloidal crystal template method,CexCo1-xMn2O4 catalyst（x=0.2,0.4,0.6,0.8）was prepared by reverse deposition in a certain proportion.The results of activity evaluation showed that Ce doping could also improve the soot catalytic performance of CexCo1-xMn2O4 system,and make the catalyst efficiently oxidize soot at about 450 degrees Celsius.（4）The catalytic performance of CexCo1-xMn2O4 catalyst increased firstly and then decreased with the increase of Ce doping amount.CexCo1-xMn2O4 catalyst（x=0.2,0.4,0.6,0.8）had the best comprehensive catalytic performance when the Ce to Co element ratio was 3 to 2.The characteristic temperature Tm=504℃ for the optimum activity of the catalyst.When the catalyst and soot contact conditions were different,the catalytic performance of the catalyst was also different,such as Ce0.6Co0.4Mn2O4 catalyst in loose contact with soot Tm was 512℃,and in close contact with soot Tm was 489℃.（5）The nanowire catalyst with special structure was successfully synthesized.The catalyst was prepared by changing the calcination temperature.It is found that the catalyst has the strongest stability and reducibility when the calcination temperature was 500℃.At the same time,the influence of various influencing factors on the performance of the catalyst was investigated.The results showed that the catalyst exhibited strong catalytic activity under the conditions of close contact,appropriate air flow rate,the lowest catalyst humidity and the mass ratio of catalyst to soot of ten to oneFigure[51]Table[13]Reference[128]... |
PDF Full Text Request